function [long_bits] = new_Extract_process_2(stego_cover)
%UNTITLED3 此处显示有关此函数的摘要
%   此处显示详细说明
long_bits='';
bits='';
for x=1:2
  for y=1:2
      extract_block=stego_cover((x-1)*2+1:x*2,(y-1)*2+1:y*2);%拿出每个2*2块
      bits=ext_bit(extract_block);
      long_bits=[long_bits bits];
  end
end
end

function bits=ext_bit(extract_block)
if mod(extract_block(1,1),2)==mod(extract_block(2,2),2)
    bits='1';
else
    bits='0';
end
if mod(extract_block(1,2),2)==mod(extract_block(2,1),2)
    bits=[bits '1'];
else
    bits=[bits '0'];
end
end
